I have done much reading on adding 2 stroke oil in diesel to make up for the ultra low sulfur fuel. I decide i would give it a shot and WOW, my 03 7.3 psd is running quieter and getting 2 more mpg. the mix ratio I decided to go with ended up being 1qt to a tank of fuel. I plan on trying it in my next tank also. A friend of mine which has a cummins has been doing this for some time and has had no problems. Has anyone else tried this?

Lessmore wrote:Two stroke oil is designed for 2 stroke engines and no other type of engine. A 7.3 IH/Ford diesel is a 4 stroke.

I wouldn't use 2 stroke oil in a 4 stroke engine. But that's just me.

True but you are not putting it into the crank case but the fuel tank.

We have a 1976 265 MF diesel tractor with less than 1300 hours on it that hammered like crazy (injector pump) until I started adding 1 oz per gallon of diesel of Walmart TCW3 oil to the fuel tank. It makes it light blue in color.I must have read about 40 hours worth of research on the subject before I felt it was a risk free option.

Some run at 500:1 ratio in gas engines for in-tank fuel pump lube and perhaps some rust control. Some claim better MPG but the informal research on that use of TCW3 did not really support a improvement in MPG but a few are certain it helped and some said it hurt MPH. I have used it in the MH especially over the winter. All I can say it did not seem to hurt anything.

Sulfur is one of the contents that actually assisted in lubrication. When they moved to ultra low sulfur diesel fuel, well that lubricity was removed from the fuel.

As a result, diesel fuel now is sometimes very dry and does not lube the pump and other parts as it should. It is that very dry fuel which is one of the suspected culprits in the high pressure fuel pump failures now being experienced by VW, Ford and GM which are running a CP 4 series Bosch pump.

The 2 stroke oil works in older diesels, but cannot be used in any of the 2007 or newer motors (someone please correct if I have the year wrong here, I know there is a date point at which due to mechanical issues, the 2 stroke oil should not be used.)

The Diesel Place.com site did a study of the various diesel fuel additives meant to add lubricity to diesel fuel. Result are found here.

The study was done a few years back now, but is still relevant. The 2 stroke oil was #7 in effectiveness in their list of additives tested.

I think the reference to the difference between two stroke and four stroke diesel technology isn't relevant to adding the oil to diesel fuel. Two stroke oil was designed to be added to the fuel for two stroke GAS engines that don't have a circulating lubricating oil system. As I understand it, two stroke oil doesn't contain the detergent added to regular lubricating oils.

Getting back to the question of adding the oil to diesel fuel to improve performance is still a question I'd like answered. Do the older diesels benefit from oil added to their fuel?

I think it depends on the injector pump types too. On the four cylinder 1983 John Deere the use of TCW3 does not change the noise level that I can tell but it does on the 1976 MF. Both are 60 HP engines.